Institute for Research and Innovation in Biomedicine, University of Rouen, Rouen, France

Identification
of biological markers is extremely important to improve patient’s care in
psychiatry and contributes to the development of new treatment options for
anxiety and depression. However, with certain exceptions, truly sensitive and
specific markers are still lacking. Several studies have reported opioid
systems dysfunction in pathogenesis of anxiety and depression. Recently we have
demonstrated that endomorphin-1 (EM-1: Tyr-Pro-Trp-Phe-NH2) and
endomorphin-2 (EM-2: Tyr-Pro-Phe-Phe-NH2), two endogenous peptides,
which bind to the µ-opioid receptors with extremely high affinity and
selectivity, displayed antidepressant-like effect in rodents. It has also been
reported that these peptides exert anxiolytic-like action. Based on these data,
we have quantified, with both HPLC and mass spectrometry methods, the brain
EM-1 and EM-2 levels, in two animal models selected according to their
divergences in anxiety and depression tests.

These results provide the first evidence of
cerebral deficiency of both EM-1 and EM-2 levels in physiopathology of anxiety
and depression. Endomorphins could thus be used as potential biomarkers to
diagnose anxiety and depressive disorders.